Gardening in Lethbridge · Plant and grow

Perennials and Annuals

Flowers that come back every year, flowers that give everything in one summer, and bulbs that come up through the last of the snow. Here’s what holds up to Lethbridge sun, wind and dry spells, how to keep perennials healthy for decades, and how a few divided plants can carry a family’s garden from one yard to the next.

⏱ 15 min readLevel: EveryoneUpdated October 2026

Perennials, annuals, biennials and bulbs

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Annuals

Grow, flower, set seed and die in one season. They bloom for months because they’re racing to make seed. Planted out after frost, around May 25 to June 1.

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Perennials

Die back to the ground each fall and come back from the roots in spring, for years or decades. Most bloom for a few weeks. Hardiness zone matters for these.

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Biennials

Grow leaves the first year, flower and die the second. Hollyhocks, foxgloves and sweet William often behave this way, but they reseed so readily they seem perennial.

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Hardy and tender bulbs

Hardy bulbs (tulips, daffodils, crocus) are planted in fall and stay in the ground. Tender bulbs (gladiolus, dahlias, begonias) are planted in spring and dug up before winter.

What it means for you: perennials are the backbone of a bed and save work over the years. Annuals fill the gaps and carry colour from June to frost. Most good Lethbridge gardens use both.

Perennials that thrive here

Every plant below is rated hardy to Canadian zone 3 or colder unless noted, and has a long track record in prairie gardens.

Plant	Best spot	Notes
Peony	Full sun	Zone 2. Can live 50 years or more in one spot. Plant the pink buds (“eyes”) only 2.5 to 5 cm deep, or it won’t bloom. Use a ring support before it grows.
Daylily	Sun to part shade	Nearly indestructible, drought-tolerant, hundreds of colours. Each flower lasts one day; the plant keeps opening new ones. Deadly to cats: even a little pollen can cause kidney failure, so skip daylilies if you have a cat.
Bearded iris	Full sun, good drainage	Loves our dry, sunny climate. See below.
Siberian iris	Sun to part shade	Zone 2. Grassy leaves and slender flowers. Tougher and more forgiving of moist soil than bearded iris.
Yarrow	Full sun, dry	Native to Alberta. Flat flower heads in white, yellow, pink and red. Handles drought and poor soil; can spread.
Blanket flower (Gaillardia)	Full sun, dry	The native Gaillardia aristata grows wild on Alberta grasslands. Red and yellow daisies all summer.
Purple coneflower (Echinacea)	Full sun	About zone 3. Drought-tolerant, loved by bees and butterflies; finches eat the seeds in fall. Newer fancy colours are often less hardy than the plain purple.
Sedum (stonecrop)	Full sun, dry	Succulent leaves store water. Tall types flower in late summer; low types make groundcovers.
Catmint (Nepeta)	Full sun	Blue-purple haze from June to fall, hums with bees, shrugs off wind and drought. Shear it back after the first flush.
Delphinium	Full sun, sheltered	Zone 2, and grows taller and bluer on the prairies than almost anywhere. Stake every stem early, before the wind does it for you.
Columbine	Part shade	Short-lived, but reseeds itself. Nodding flowers loved by hummingbirds.
Hosta	Shade	Zone 3. The go-to shade plant. In Lethbridge sun, give it real afternoon shade and steady water.
Bergenia	Part shade	Big, leathery leaves that turn red in fall; pink flowers in early spring. Tough in dry shade.
Lily-of-the-valley	Shade	Zone 2, fragrant, but spreads aggressively and is very hard to remove. All parts are poisonous. Plant only where it can’t escape.

Poisonous if eaten: delphinium, foxglove, monkshood, lily-of-the-valley and daffodil bulbs (which look a lot like onions) are poisonous to people and pets. Store bulbs away from the kitchen, and teach children never to eat garden flowers. See garden safety.

Native prairie options

Plants that evolved on our grasslands need almost no water once established and feed native insects. Look for nursery-grown prairie crocus (pasqueflower), blue flax, three-flowered avens, wild bergamot, harebell and the native blanket flower. Prairie crocus is often the first flower of the year on the coulee slopes, sometimes opening in April with snow still around.

Never dig native plants from the wild. Prairie crocus has a deep taproot and rarely survives being moved, and digging on public land or the coulees damages a habitat that’s slow to recover. Buy nursery-grown plants or collect a few seeds instead.

Bearded iris, and passing plants along

Bearded iris is made for Lethbridge. It wants full sun, dry summers and soil that drains, and it hates having its roots sitting wet. The stylized iris flower, the fleur-de-lis, has been a symbol in France and Quebec for centuries.

From experience

Esther’s lilies. The iris in my yard, the fleur-de-lis, came from the old acreage where I grew up. My uncle always called them “Esther’s lilies,” after my mom, Esther. My sister Barb kept them going and shared some with me, I planted them here, and I’ve given some to my daughter for her garden. They live on. — Gary

How to divide and share bearded iris

Bearded iris grows from a rhizome, a thick, fleshy stem that creeps along the top of the soil. Over the years the clump gets crowded, the old centre goes bare, and flowering drops off. Dividing every three to five years keeps it blooming, and gives you plenty to share.

Wait until after bloom, in July or August. The plant has finished flowering and has time to root in before winter.
Lift the whole clump with a garden fork, working in from the edges so you don’t spear the rhizomes.
Break or cut it apart. Keep healthy pieces with at least one fan of leaves and a firm rhizome about the size of a finger or bigger. Throw away the old, leafless centre and anything soft or mushy.
Trim the fans to about 15 cm tall, in an upside-down V. This cuts water loss while new roots form, and keeps the wind from rocking the piece loose.
Replant shallow. Make a small mound in the hole, set the rhizome on top with the roots spread down either side, and cover the roots but leave the top of the rhizome showing, at the soil surface, where the sun can bake it. Space pieces 30 to 45 cm apart, fans pointing outward.
Water once to settle them, then go easy. Too much water after dividing is more harmful than too little.

Pass-along plants. Many of the toughest perennials in Lethbridge yards were never bought. They came as a clump in a bucket from a parent, a neighbour or a friend: iris, peonies, daylilies, rhubarb. When you divide, pot up the extras. The Lethbridge & District Horticultural Society holds plant exchanges where divisions like these find new homes, and where you can often learn the story behind a plant along with how to grow it.

Annuals for heat and wind

Our strong sun, dry air and wind are hard on soft, floppy annuals and easy on tough, sun-loving ones. These earn their spot:

Annual	Why it works here
Marigold	Loves heat, blooms nonstop, low and sturdy. Easy from seed started indoors in mid-April.
Zinnia	Thrives in hot, dry sun. Great cut flower; the more you cut, the more it blooms. Choose shorter types in windy spots.
Cosmos	Airy and drought-tolerant. Tall types need shelter or staking.
Petunia	Handles sun and heat; trailing types are hanging-basket favourites. Start early (early March) if growing from seed.
Geranium (pelargonium)	Heat- and drought-tolerant, perfect for pots. Can be overwintered indoors in a sunny window.
Snapdragon	Handles cool spring nights and a light frost; blooms into October. Kids love squeezing the “dragon’s mouth.”
Sunflower	Sow straight in the ground in late May. Plant tall types where a fence breaks the wind.
Sweet alyssum	Low, honey-scented edging that takes light frost. Reseeds.
Nasturtium	Grows well in poorer soil (rich soil means leaves, not flowers). Flowers and leaves are edible and peppery.

What it means for you: wait until about May 25 to June 1 to plant annuals out, and harden off greenhouse plants for a week first. They’ve never felt wind. A late-May frost can wipe out a whole bed of bedding plants in one night. See frost dates and starting seeds indoors.

Spring bulbs: plant them in fall

Tulips, daffodils and crocus need a long cold spell to bloom, which Lethbridge provides in abundance. Plant them in late September to October, while the soil is still workable and there’s time for roots to grow before freeze-up.

Depth: about three times the height of the bulb, pointy end up. Tulips and daffodils go 15 to 20 cm deep; crocus and scilla about 8 to 10 cm.
Drainage: bulbs rot in soggy clay. Choose a well-drained spot or a raised bed.
Tulips tend to dwindle after a few years. Small “species” tulips and some Darwin hybrids come back more reliably.
Daffodils are long-lived, and squirrels and deer leave them alone.
Crocus and Siberian squill (Scilla) are among the first flowers of spring, and an early meal for bees. Scilla spreads into carpets of blue under trees.
Ornamental onions (Allium) bloom in early summer with purple globes on tall stems, after the tulips have gone.
After bloom, let the leaves yellow and die back on their own. They’re feeding next year’s bulb.

From our weather station

A spring chinook can bring bulbs up early, and then a cold snap follows. Don’t worry: tulip and daffodil leaves are built to take frost and even snow. If a hard freeze hits while they’re in full flower, cut a few for a vase before it comes. Check the forecast.

Gladiolus and other tender bulbs

From experience

The gladiolus garden. When I was a kid we lived on a five-acre plot with a huge garden, and every year part of it was set aside for a gentleman who grew prize gladiolus for competition. Looking out over all those colours is something I’ve never forgotten, and gladiolus have been one of my favourite flowers ever since. — Gary

Growing gladiolus in Lethbridge

Gladiolus grow from a corm, a flat, solid bulb-like base that won’t survive our winters in the ground. Grown as a summer flower and lifted each fall, though, they do beautifully in our sun.

Plant after the last frost, starting around late May, in full sun. Set corms pointed end up, 10 to 15 cm deep. Deeper planting helps anchor the tall stems against wind.
Stagger the plantings. Plant a batch every one to two weeks from late May through June. Each corm takes roughly two to three months to bloom, so staggered batches give you flowers from midsummer until frost instead of all at once.
Stake against wind. A full flower spike is heavy and acts like a sail. Put in a stake at planting time, or plant in a block along a fence and run twine around the group. Hilling a little soil around the stems helps too.
Water deeply once a week in dry weather, especially once the flower spikes appear.
Cut for the vase when the bottom one or two flowers open. The rest open in water. Leave at least four leaves on the plant to feed the corm.
Dig after the first frost blackens the leaves in September or early October. Cut the stems off a few centimetres above the corm.
Dry and store. Spread the corms in a warm, airy place for two to three weeks. Then snap off the old, shrivelled corm underneath and keep the new one (and the tiny cormlets if you want to grow more). Store them in mesh bags or paper in a cool, dry, frost-free place, ideally around 5 to 10°C, until spring.

Other tender summer bulbs

Dahlias: start tubers in pots indoors in April for earlier flowers, plant out in early June, stake the tall types, and dig after frost. Store tubers in slightly damp peat, sawdust or vermiculite, cool and frost-free.
Tuberous begonias: start indoors in March or April. Perfect for shady patios and pots out of the wind; their stems are brittle.
Canna: big tropical leaves for a hot, sheltered corner. Start indoors, plant in early June, and dig the rhizomes after frost.

Containers and hanging baskets in wind

Pots let you grow flowers anywhere, but in Lethbridge they also dry out faster than anything else in the yard, and the wind treats a hanging basket like a wind chime.

Go big and heavy. Larger pots hold more water and don’t tip. Ceramic or a stone in the bottom helps; a 30 cm pot dries out much more slowly than a 15 cm one.
Water every day in summer, sometimes twice in hot wind, until water runs out the bottom. Self-watering pots and a layer of mulch help.
Feed regularly. Daily watering washes nutrients out. Use a diluted fertilizer every week or two, or mix compost into the potting soil.
Hang baskets in the lee of the house, on the east side, out of the west wind. On a stormy day, take them down and set them on the ground.
Choose wind-tough plants for exposed balconies: geraniums, marigolds, trailing petunias, ornamental grasses and sedums rather than tall, brittle flowers.
Watch for frost. Pots freeze faster than ground. Bring them in on frosty nights in late May and September.

Dividing, deadheading and fall cleanup

Dividing perennials

Most perennials need dividing every three to five years, when the centre dies out or the flowers get smaller. A rough guide: divide spring and early-summer bloomers in late August or September, and late-summer bloomers in spring as new growth starts. Bearded iris is the exception, done in July or August. Peonies are best left alone; if you must move one, do it in September and keep the eyes shallow.

Deadheading

Snipping off faded flowers stops a plant from making seed, so many annuals and some perennials (daylilies, coneflowers, catmint, petunias, marigolds) keep blooming longer. Leave the last flush of seed heads on coneflowers and sunflowers in fall for the birds.

Fall cleanup, or not

Tidy gardeners like to cut everything to the ground in fall. In Lethbridge there are good reasons not to:

Snow catch. Standing stems trap blowing snow, and snow is the best winter insulation a perennial can get. In a dry, windy winter, it also means more moisture in spring.
Homes for insects. Many native bees and other helpful insects spend the winter in hollow stems and leaf litter.
Food for birds. Seed heads feed chickadees and finches through the winter.
What to remove: diseased or mushy foliage (peony and iris leaves, anything with leaf spot), and plants that reseed too freely. Cut the rest back in spring, once daytime temperatures are reliably above about 10°C, so overwintering insects have woken up.
Mulch after the ground freezes, not before, to keep it frozen through chinooks and prevent heaving.

A garden for pollinators

Alberta has hundreds of species of native bees, from big fuzzy bumblebees to tiny solitary bees most people never notice. Many of them pollinate our fruit and vegetables. A few simple choices make a yard much friendlier to them:

Bloom from April to October. Crocus and scilla in early spring, then saskatoons and fruit trees, catmint and peonies in June, coneflowers and blanket flower in summer, sedum and asters into fall.
Plant in clumps of three or more of the same flower, so bees can find and work them easily.
Include natives such as yarrow, blanket flower, wild bergamot and prairie crocus.
Leave some bare, sunny ground. Most native bees nest in the soil, not in hives.
Offer water: a shallow dish with pebbles to land on, refilled often in our dry heat.
Skip the sprays entirely. A blast from the hose deals with most aphids.

Kids’ corner

How do bees find flowers? Bees see colours we can’t, including ultraviolet. Many flowers have hidden ultraviolet stripes and spots that point like a runway to the nectar. Bees also follow scent, and scientists have found that bumblebees can even sense the tiny electric charge around a flower, which tells them if another bee has visited it recently.

Wonder: young sunflowers turn to follow the sun across the sky each day. Grown-up sunflowers stop and face east. Why might a flower want to face the morning sun? (Hint: warm flowers get more bee visits.)

Try this: a sunflower height contest. In late May, each person plants a few seeds of a tall sunflower variety along a sunny fence and picks the strongest seedling. Measure your sunflower every Saturday and mark it on a chart. Whose grows tallest by the end of August? Then count how many seeds are in the head.

Sources

Natural Resources Canada, Plant Hardiness of Canada.
University of Saskatchewan, Gardenline perennial, bulb and annual growing pages.
Lethbridge & District Horticultural Society, Perennial Plant Exchange announcements.
Clarke, D. et al. (2013), “Detection and learning of floral electric fields by bumblebees,” Science.
Atamian, H. S. et al. (2016), “Circadian regulation of sunflower heliotropism, floral orientation, and pollinator visits,” Science.
Environment and Climate Change Canada, Canadian Climate Normals 1981–2010, Lethbridge CDA, frost probabilities.

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